Kidney disease develops in 25% to 40% of diabetic patients, usually 20 to 25 years after the onset of diabetes. Approximately one third of those with diabetic kidney disease (DKD) will progress to end-stage kidney disease (ESKD) and will require long-term dialysis or possibly receive a kidney transplant. Many patients however may die from associated coronary artery disease or other cardiovascular causes before the onset of ESKD. Antihypertensive drugs have been shown to not only be of benefit to the heart but to also provide kidney protection by slowing the progression of DKD to ESKD. Two drugs in particular have been considered equally effective for patients with DKD - these are angiotensin converting enzyme inhibitors (ACEi) and angiotensin II receptor antagonists (AIIRA). However studies have focused on kidney protection rather than over mortality. The aim of this review was to assess the benefits and harms or ACEI and AIIRA therapy in patients with DKD. Fifty studies (13,215 patients) were identified comparing ACEi to placebo, AIIRA to placebo and ACEi to AIIRA. The risk of death from any cause was not significantly reduced with the use of ACEi versus placebo, AIIRA versus placebo or ACEi versus AIIRA. However when we looked at the studies which used the maximum dose tolerated of ACEi rather than the lower, so-called renal doses, there was a significant reduction in the risk of death due to any cause. We were unable to determine which drug provides better protection due to the lack of head-to-head trials.

Authors' conclusions:

Although the survival benefits of ACEi are known for patients with DKD, the relative effects on survival of ACEi with AIIRA are unknown due to the lack of adequate direct comparison studies. In placebo controlled studies, only ACEi (at the maximum tolerable dose, but not lower so-called renal doses) were found to significantly reduce the risk of all-cause mortality. Renal and toxicity profiles of these two classes of agents were not significantly different.

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Background:

Angiotensin converting enzyme inhibitors (ACEi) and angiotensin II receptor antagonists (AIIRA) are considered to be equally effective for patients with diabetic kidney disease (DKD), but renal and not mortality outcomes have usually been considered.

Objectives:

To evaluate the benefits and harms ACEi and AIIRA in patients with DKD.

Search strategy:

We searched MEDLINE (1966 to December 2005), EMBASE (1980 to December 2005), the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library issue 4 2005) and contacted known investigators.

Selection criteria:

Studies comparing ACEi or AIIRA with placebo or each other in patients with DKD were included.

Data collection and analysis:

Two authors independently assessed trial quality and extracted data. Statistical analyses were performed using the random effects model and results expressed as risk ratio (RR) with 95% confidence intervals (CI). Heterogeneity among studies was explored using the Cochran Q statistic and the I² test, subgroup analyses and random effects meta-regression.

Main results:

Forty nine studies (12,067 patients) were identified. Thirty eight compared ACEi with placebo, four compared AIIRA with placebo and seven compared ACEi and AIIRA directly. There was no significant difference in the risk of all-cause mortality for ACEi versus placebo (RR 0.91, 95% CI 0.71 to 1.17) and AIIRA versus placebo (RR 0.99, 95% CI 0.85 to 1.17). A subgroupanalysis of studies using full-dose ACEi versus studies using half or less than half the maximum tolerable dose of ACEi showed a significant reduction in the risk of all-cause mortality with the use of full-dose ACEi (RR 0.78, 95% CI 0.61 to 0.98). Baseline mortality rates were similar in the ACEi and AIIRA studies. The effects of ACEi and AIIRA on renal outcomes (ESKD, doubling of creatinine, prevention of progression of micro- to macroalbuminuria, remission of micro- to normoalbuminuria) were similarly beneficial. Reliable estimates of effect of ACEi versus AIIRA could not be obtained from the three studies in which they were compared directly because of their small sample size.